Dye-Based Composites

Figure 10.7 Electrophoretogram of dendritic nucleic acid 4 (lane 2) and a linear analog of identical base composition (lane 3). Lanes 1 and 4 marker dyes xylene cyanol (XC) and bromophenol blue (BPB). (Reprinted with permission from reference 23, copyright (1993) American Chemical Society.)...

A calcium ion indicator dye (based on the structure of the chelator EGTA) that exhibits a strong fluorescence at 385 nm and can be used to measure changes in intracellular Ca concentration. The approximate dissociation constant for the Ca -Fura-2 complex is 0.1 juM, depending on cellular ion composition and pH. An esteri-fied derivative of Fura-2 readily crosses the peripheral membrane of many cells and, after hydrolysis, the release of Fura-2 permits calcium ion measurements within cells. See Calcium Ion Indicator Dyes Metal Ion Complex-ation... 

In Table 11, photopolymerization speeds were measured by step-wedge exposure in film-based compositions containing MB and a triacrylate monomer. The comparison, largely for amine-type activators and enolates, shows only a 5x variation in viscous films compared to approximately 20x for similar activators in solution. The absolute loss in system photospeed on changing from solution to film composition is estimated to be near 60x for NPG and TBBS. This loss of reactivity is presumed to be caused by viscosity differences between the two media reflected in lower overall sensitization efficiency in films as a result of increased competition of dye radiationless decay relative to bimolecular quenching. 

For solution phase photopolymerization, photosensitive solutions must be prepared immediately before use. In film-based compositions, stability and sensitivity are lost in 2-5 days (compare Tables 6, 10). The lack of stability is directly related to the nature of the activator, although not in a way that necessarily parallels photosensitivity. The photoactivated reaction, dye-activator redox chemistry, is a go/no-go process and does not contribute to the dark reaction. Rather, dark reactions are in general a consequence of the basicity of most common activators, for example, amines, sulfinates, or enolates. Deprotonation of active methylene groups on some dyes (e.g.,... 

In this paper, we attempt to elucidate the thermodynamic quantities of the interaction in the dye binding by intercalation process and also explore the effect of GC base composition of DNA on dye binding by measuring the heat of mixing of proflavine (PF) and Cl. perfrlngens DNA (DNA I), E. coll DNA (DNA II) and M, lysodelktlcus DNA (DNA III), respectively because the interaction for Intercalation process is based on the interaction between dye and base pairs of DNA. 

Thiadiazoles have attracted significant interest in medicinal chemistry and many fields of technology. Some of the technological applications involve dyes, lubricating compositions, optically active liquid crystals, and photographic materials. In medicinal field, one of the best-known drugs based on 1,3,4-thiadiazole is the acetazolamide (Acetazola), which is a carbonic anhydrase inhibitor launched in 1954. 

The resulting DBCs were characterized in several ways. In agarose gel electrophoresis, the DBCs exhibited a lower electrophoretic mobihty than the pristine DNA amphcons of the same number of nucleotides. Furthermore, the base composition of the DBCs was verified by DNA sequencing employing the dye-terminator procedure [29], which revealed a perfect match with the sequence of the template. A third method of stmctural proof of the DBCs involved restriction analysis with sequence-specific endonucleases. 

As an alternative, special dyes based on phthalocyanine derivatives have been proposed (67). In addition, bronzing inhibitors have been tested, such as 3-hydroxy-2-naphthoic acid or 4-hydroxybenz-oic acid. Related compounds show less bronzing inhibition. The compositions have been detailed (67). 

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